Containers under pressure, containing compounds such as pastes, foams or glues, find increasing use in the building industry as well as in do-it-yourself (DIY) activities. These containers are usually disposable pressure containers, closed off by a relatively simple valve but which needs to withstand the significant pressures which may occur inside the container. Generally two types of applicators are used in current practice. Occasional and DIY users typically prefer a simple handheld applicator, usually also disposable, which is typically screwed onto the stem of the valve of the container and usually comprises a hose or tube for guiding the flow of the compound to its intended location, and a tilting adaptor or lever. Such handheld applicators are characterised in that they do not themselves contain a valve for stopping or controlling the flow of compound, but act on the valve provided on the container for those purposes. Consequently, any compound having passed the container valve and entered the handheld applicator is exposed to the atmosphere and, if susceptible, may react further and convert into its ultimate and usually rigid consistency. For these reasons, these adaptors are simple in design and production, cheap, but most often only useable once, and thus disposable. Typically an action on the tilting adaptor or lever provided as part of the handheld applicator results in a tilting or pushing down of the stem of the container valve, such as in its surrounding rubber grommet in case of a conventional valve, relative to the cup of the valve, such that one or more openings in the valve stem are set free into the container contents, thereby opening the container valve. The assembly is such that the user may hold the container while pushing the handheld applicator, which provides a rough means for controlling and dosing the compound flow. U.S. Pat. No. 4,165,825 discloses suitable valves for such handheld applications. The compound dosing with such handheld systems is however rather inaccurate and such a system is therefore more suitable for filling large crevices or cavities, such as those wider than 2 cm.
The more intensive users, such as professionals or more experienced DIY users, typically prefer a more sophisticated dispensing device, such as a foam-dispensing gun, for applying the compound. With such dispensing devices, the user holds and manipulates the device or foam-dispensing gun, with the compound container being attached to the gun. Such guns are characterised in that they comprise their own valve, preferably a needle valve for higher accuracy and better closure, for stopping or controlling the flow of compound, and this valve is usually located at the tip of the gun barrel and much more sophisticated than the container valve. It typically allows for a much better control of the compound flow as compared to the container valve. Because the valve is located at the tip of the barrel, there remains after use little to no volume of compound which has been exposed to the atmosphere and may react and become rigid. The compound inside the dispensing gun remains under pressure and sealed from the atmosphere, except for the short time required for exchanging a container on the dispensing gun. This time is usually short, and the dispensing gun is typically used immediately after the exchange, such that the compound inside the dispensing gun is refreshed and after use this new compound remains under pressure and fresh in its fluid state. These dispensing guns are usually more complex and expensive and are typically reused several times after replacing the previous empty container with a fresh and full one. The use of these dispensing guns is more comfortable for the user, and allows a higher accuracy and dosing in the application of the compound than the handheld system. Dispensing guns are therefore also preferred for filling up smaller crevices, such as those smaller than 2 cm wide. The higher dosing accuracy allows working with less excess compound, which usually needs to be removed later and ends up as waste. This reduces the amount of aftercare work required and brings a higher efficiency in material use. Both these advantages are of high interest to the professional or intensive user.
Containers intended for the intensive user are for this purpose conveniently provided with a first coupling piece, usually made from a plastic material, which makes the container suitable for attachment to the dispensing gun or dispensing device, and which matches with a connection element integrated in the dispensing gun, or with a second coupling piece which is attached to the dispensing gun, also called a gun adaptor, usually made of metal, such as aluminium or bronze, for making the coupling with the dispensing device or dispensing gun. A suitable foam dispensing gun is for instance disclosed in U.S. Pat. No. 5,271,537, whereby the device comprises a screw connection into which a container may be screwed which has a suitable screw connection, usually by means of a suitable coupling piece on the container.
The first coupling piece of such a screw connection typically surrounds the valve which closes off the container. The screw coupling is usually provided such that when the screw connection is being effected, usually by manually tightening the screw until the stop position is reached, at the same time the valve of the container is brought into the open position and flow of the compound in the container is made possible from the container into the dispensing gun, where it may be stopped and/or controlled by the valve in the dispensing gun. For this purpose, a central internal extension is usually provided on the dispensing gun, or as part of the second coupling piece or gun adaptor, which upon effecting the coupling engages with the stem of the container valve and pushes the valve down in the open position, at the same time providing a seal around the stem of the container valve such that the compound is only allowed to flow via the intended channel through the dispensing gun and avoiding any escape of compound into undesirable locations, where it would foul up the coupling pieces or the dispensing gun. The screw coupling typically requires a plurality of full windings in multiple manual handling steps in order to effectuate the coupling.
It should be noted that the first coupling piece needs to be strongly attached to the container, because the connection needs to withstand the force required for opening the container valve, as well as the force exerted by the pressurized content of the container on the dispensing gun when the valve is opened. It also needs to withstand the torque force when the screw connection is being effected.
As it is commercially offered with its content under pressure, the container or canister intended for use with the dispensing gun is thus typically different from the container intended for handheld use, i.e. with a handheld applicator. The container for professional use is thus usually provided with a first coupling piece which is so strongly attached to the container that its removal, which would be required to allow attaching the handheld applicator for handheld use to the stem of the container valve, would require a prohibitively strong force for the typical occasional or DIY user. It would also lead to unsafe situations, e.g. creating a risk for unintentionally ripping off the valve. Consequently the supply chain has been carrying two types of containers having different designs, one designed for use with the dispensing gun, and the other for use with the handheld applicator.
The containers itself are typically made of metal and are usually cylindrical in shape. The bottom is usually formed by a plate flanged to the cylinder and typically is concave for better withstanding the internal pressure while maintaining the ability for the container to stand upright on a flat surface. The top is usually provided with a container head, also flanged to the cylinder, and which is typically convex for the same reason of higher pressure resistance. A filling opening is usually provided centrally in the cylinder head. When preparing the container for the market, the empty container is typically filled with the compound through this central filling opening in the head, which subsequently may be closed off by flanging the container valve into the filling opening. Many compounds may be filled into the container under atmospheric pressure, and a higher pressure may subsequently be built up or introduced into the container, usually after it is closed off as described. An example wherein pressure builds up after closing the container are the compounds for polyurethane foam, in particular the one-component-foam (OCF), in which, after filling the container, an exothermic chemical reaction between the compounds may be initiated, such as by shaking the container, and the reaction produces heat and builds up pressure by the chemical production and/or the vaporisation of propellants. Propellants for building up the pressure may also be introduced at the moment of filling the container, such as a cold liquid which then is allowed to vaporise after closing the container.
We have found that the valve cup, i.e. the metal part of the container valve which is flanged to the container head and supports the rubber grommet through which sticks the typically plastic stem of the valve, may be pushed outward when the pressure builds inside the container, especially when the exothermic reaction temporarily also raises the temperature. This may have as an effect that the valve, in particular the valve stem, moves away from its initial position. We have also found that the distance that the valve stem may be moved may vary from container to container, and that this distance is difficult to predict as it depends a.o. on the internal pressure in the canister. This brings as a result that the valve stem position may be different from the expected position and not anymore optimal for when the coupling has been effectuated. This repositioning of the valve over an unpredictable distance may thus affect the opening of the valve when the coupling between the container and the dispensing gun is made, such that, upon closing the coupling, the valve may not always reach a desirable degree of opening, or may not open at all, or reversely the valve may open too soon and cause accidental spillage of compound. The screw coupling becomes more vulnerable to this problem the smaller the rotational movement is which is chosen for fully connecting the two coupling pieces.
The containers of the present invention may comprise, under pressure, compounds which are still highly reactive and react out after the compound has been applied into its final location, such as in a crevice or on to a substrate. Contact of the container content with skin, or even more importantly with eyes, is therefore to be avoided. For safety reasons, the containers ready for market are therefore always provided with a protecting cap, which is supposed to shield the container valve and in particular the valve stem from being damaged, ripped off or being touched and moved relative to the valve cup, and thus for reasons of safety and for protecting against accidental spillage. The containers for handheld use are typically supplied without a coupling piece, i.e. with the valve fully accessible. Therefore such containers are conventionally supplied with a separate shielding cap which is usually clicked onto the flange around the container head. The containers for professional use are provided with the first coupling piece, typically snapped onto the flange around the valve cup. Access to the valve stem through this first coupling piece is then typically closed off with a separate cap, which may for instance snap onto the upper rim of the coupling piece, which may be suitably adapted for snapping on the cap, such as by providing a small collar.
Separate caps have been designed, and the head of the coupling piece on the container may be made suitable to accept these caps as seals for the valve compartment. This design requires the separate production of a cap and the need for an extra step in the assembly of the container, i.e. to put the cap onto the head of the coupling piece.
This shielding cap thus represents an extra element which needs to be produced separately and needs to be assembled with the coupling piece before or after attaching the coupling piece on the container. The shielding cap for the container intended for handheld use also represents a separate assembly element. These caps therefore create an extra burden in the supply chain of the containers, in the sense that there is a need to carry two types of containers and for both types an extra assembly element has to be provided and assembled.
There has therefore been a need for a two-in-one design, i.e. a container which would be suitable for use with a dispensing gun as well as with a handheld applicator, and/or a handheld applicator which would be suitable for use with the container assembly intended for use with the dispensing gun.
We have also found that there exist a variety of dispenser devices or gun applicators for the screw coupling, but all do not necessarily expect the stem of the valve of the container to be in exactly the same position relative to the screw threaded section of the first coupling piece. In addition, as explained above, the valve cup may become bulged or pressed outward by the internal pressure, and temperature, building up in the container after filling and closing, possibly after homogenising its content for starting the chemical reaction. This may further lead to a mismatch between the container valve stem location and the dispenser device or gun applicator, and may thus lead to suboptimal performance, such as unintentional leakage of compound when the container is coupled to the gun applicator.
WO 2007/112758 discloses a handheld applicator which may be fastened onto the valve stem of a container intended for use with a dispensing gun. The handheld applicator may then be “clicked” directly on the valve-stem. The difficulty with this design is that fastening of the handheld applicator onto or off the valve stem needs to be performed very carefully, as any tilting of the valve would cause premature and unintentional spillage of compound, and any damage to the valve may create a safety hazard.
US 2007/0181610 A1 discloses a handheld applicator which is suitable for being snapped onto the flange around the container valve. The drawback with this proposal is that the first coupling piece, with which a container for use with a dispensing gun is usually sold, needs to be removed from the container before the flange is available for snapping on the handheld applicator. The difficulties and safety issues of such a removal have been discussed above. Such manipulation is strongly disadvised because of the safety risks involved, especially the risk for getting compound into the eyes. A further problem may occur when the container valve has moved under the internal pressure of the container.
Other systems have been developed, where a handheld applicator may be screwed into a threaded internal section of the coupling piece intended for the dispenser device. The difficulty with such systems is that the valve opens while the applicator is being screwed into place, and the degree of screwing defines the opening of the valve and thus the flow of the compound. Especially occasional users prefer to use their two hands for screwing on the applicator, and it is very difficult to achieve, at the same time while screwing on the applicator, also a good and accurate application of the compound. Another coupling piece with a threaded internal section is for instance described in FIGS. 13 and 14 of WO 2009/004097. In the assembly with the container disclosed in WO 2009/004097, the valve cup is still given the freedom to deform, bulge or be pushed outward under the pressure which builds inside the container after filling and closure. The risk remains that the valve cup deforms, and that the stem of the container valve moves away from its initial position, such that any coupling with a gun dispenser or a handheld applicator is suboptimal.
DE 3518627 A1 discloses a two-part coupling piece wherein the first external part is provided with circular grooves, and the second internal part is provided with ring-shaped protrusions. The internal part is inserted after fitting the first external part over the valve flange of a container, and reinforces the connection of the coupling piece with the container. Also in the assembly with the container disclosed in DE 3518627 A1, the valve cup retains the freedom to deform, bulge or be pushed outward under the pressure which builds inside the container after filling and closure. The risk remains that the valve cup deforms, and that the stem of the container valve moves away from its initial position, such that any coupling with a gun dispenser, or with a handheld applicator provided with similar ring-shaped protrusions, would be become problematic.
Improved coupling pieces have also been designed for attachment to the container, whereby an integrated cap is provided for manually being broken off from the coupling piece, and upon removal providing access to the valve of the container. In some versions these integrated caps are made such that the cap, after having been broken off, may be replaced again onto the coupling piece, such that the valve compartment may be reclosed, such that a partially used container may be transported and stored safely and conveniently before being used again. Improved coupling pieces having these features have been designed such that they may be produced as one single product in a single production step, such as by a single injection moulding step. This design of a coupling piece with integrated cap for single step production is however incompatible with the provision of the internal rim, also called the “support ring” which is desired for offering additional and exterior support to the valve cup, such that the valve stem is retained in place when the pressure inside the container builds up, such as part of the Click-and-Fix system disclosed in WO 98/43894.
There therefore remains a need for a two-in-one design, i.e. a coupling piece for coupling a container with a dispensing device or dispensing gun, which at the same time also provides the possibility without having to first remove the coupling piece for coupling the container with a handheld applicator, i.e. for handheld use, and which applicator only may open the container valve after the handheld applicator has been coupled to the coupling piece and the container, and which assures the dimensional stability of the valve cup, such that upon coupling with the dispensing gun or with the handheld applicator, the risk for unintentional leakage of compound from the container is reduced and preferably avoided. There remains the further need for having this improved coupling piece provided with an integrated cap and also with internal legs providing exterior support for the valve cup, and which may also be produced as a single product in a single production step.
The present invention aims to obviate or at least mitigate the above described problem and/or to provide improvements generally.